Well, it depends on the way you do it. I usually do the first few waves on the beginning, tweak my team a bit depending on what I learn from the first battles. When I began to take too much casualties and fear of losing a battle I switch to leveling the team.
Then for two weeks I do my dailys battles only with that team, which in itself I consider a part of the event as it's a very unusual team.
And in the last week I go back to go as far as I can in the waves.
True it's less intensive than other events, but it's far less grindy and I like that.